Up to 10% of households will miss out on the full Freeview digital TV service, regulator Ofcom has admitted.
The most basic Freeview package has about 18 channels
Freeview is broadcast in six "bundles" of multiple channels, three commercial and three public service.
Ofcom said the public service channels, including BBC One, ITV1 and Channel 4 must reach 98.5% of households.
But channels such as UKTV History and Sky Sports News only have to reach 73%. of households. They are set to reach 90% by 2012, when the UK turns digital.
The figure of 73% is roughly the current coverage of the commercial channels.
This will be increased at switchover because the power of the digital signal, currently kept low to avoid interference with the old analogue signal, will be increased.
Digital UK was set up to co-ordinate and publicise the UK's gradual change to a purely digital TV signal.
Spokesman John Steel said: "It's a commercial decision for the non-public service broadcasters.
"Using 80 transmitters they can reach about 90% of UK households but to get the extra few per cent they would need to access nearly 1,000 extra transmitters.
"It's still a big step forward for everyone, it's just a smaller big step for some people."